Trigonometrical meter.



PATBNTED 00T. 4. 1904.

H. o. PBRGY.

TRIGUNOMBTRICAL METER.

APPLICATION FILED MAY 14. 1904.

2 SHEETS-SHEET 1.

N0 MODEL.

WITNESS ATTOHNEYS.

PATENTED OCT. 4. 1904.

H. C. PERGY.

TRIGONOMETRIGAL METER.

APPLICATION FILED MAY 14. 1904.

2 SHEETS-SHEET 2.

NO MODEL.

Mw. mp e.. r .a H,

Arron/vf Ys v UNITED STATES vPatented October 4, 1904.

HARRY C. PERCY, OF NATCHITOCHES, LOUSIANA.

TRIGONOMETRICAL METER.

SPE(} II"I('}.ATI(I)1\T forming part of Letters Patent N0. 771,663,dated October 4, 1904. Application iiled May 14, 1904-.. Serial No.207,966. (No model.)

' zen of the United States, residing at Natchitoches, in the parish ofNatchitoches and State of Louisiana, have invented a new and usefulImprovement in Trigonometrical Meters, of which the following is aspecification.

My invention is in the nature of a trigonometrical meter designed to beused by surveyors in the iield by which they can lind withoutcalculation the distance to any remote object or the height of an objectand which is also serviceable in schools for the clearer teaching oftrigonometrical functions, since it shows for any angle the justproportions between the dierent lines within and without the circle tothe radius, suoli as the sine, cosine, secant, tangent, and versine.

It consists in the novel construction and arrangement of the instrument,which will be hereinafter fully described, and pointed out in theclaims.

Figure 1 is a plan View of the instrument. Fig. 2 is a section on theline 2 2 of Fig. 1, and Fig. 3 is a diagram illustrating' the use of myinstrument for inding distances.

Referring to Fig. l, R is a radial arm pivoted at A and having alongitudinally-sliding extension R R2 is a similar radial arm of equallength to R, but pivoted about another center, A. S is a straight bargraduated for distances in feet, progressing from the upper to the lowerend. This bar is pivoted atl) to the end of the radial arm R and at itsother end is pivoted to the free end of the radial arm The bar S swingswith the ends of the two arms R and R2, and as these arms are vof equallength the graduated bar S has a parallel motion in its variousadjustments. G is a fixed and graduated base-line scale mounted on thetable-surface W, and T is a xed and graduated tangent-bar, also mountedon the table-surface and occupying a position at right angles to thebase-scale Gr. This base-scale extends from the center A of the radialarm R to the right-angular tangent-bar T. The tangent-bar T (see Fig. 2)is slightly raised above the table-surface l/V, and beneath it isextended the end of the extensible section R of the radial arm. Thisextensible section R is graduated (see Fig. 1) and bears at its outerend a pointer fr, passing over the graduation of the tangent-bar T, andhas also on the under side a pin t, which extends through a long slot sin the table W and enters the thread of a long traverse-screw U. Thisscrew isjournaled in bearings below the table W, and said long screw andslot are arranged beneath and exactly parallel with the tangent-bar Tabove the table. The screw is provided with a milled head a, and whenthe screw is turned it causes the pin tof extensible section R" totraverse the thread lengthwise, and as it moves in a straight line itcauses the radial arm R to swing and its sliding extension R/ to bedrawn out or forced inwardly in the line of the radial arm, alsoimparting a lateral parallel motion to bar S. The radial arm R andbase-scale G being of the same length and a circle V being described bythe arm R as a radius, this circle will join the base-scale G at itspoint of intersection with the tangent-bar T, and the instrument willthen represent the various trigonometrical functions, as follows: R isthe radius. R-l-R will be the secant; T, the tangent. The distance D toE measured on bar S will be the sine., The distance A to E measured onthe basescale G will be the cosine, and the` distance E to B on thebase-scale will be the versine. It will also be seen that the relationof these several trigonometrical functions to each other will be truefor all varying adjustments of the radial arm, as shown, for instance,in dotted lines, since bar S is always perpendicular to base G in saidadjustment. As the extension R, bar S, base G, and tangent T aregraduated, any change in the position of the movable parts indicates atonce without calculation the values in igures of the varioustrigonometrical functions. Thus assuming the base-line scale Gr to havea maximum of six hundred feet and the tangent T a similar' graduation upto six hundred feet, then with the instrument in the full-line position,in which the radius R makes an angle with G at A of fortyive degrees,the sccant (A to C) will be 848.53 feet or the radius R six hundred feet(same as base) plus the readings of section R, which is 24S. 53 feet.The sine (D to E) will be 424.26 feet, the cosine (A to E) will be 2%.26feet,

IOO

the versine (E to B) 175.74 feet, and the tangent six hundred feet. InWhatever position the'movable member may be placed by the ad-Iiusting-screvv the numerical readings change in proper proportion andare at once observable Without calculation.

I Will now explain how the instrument may be applied to measuring ofdistances. For this purpose a compass X is concentrically mounted at Aabove the pivotal center oi' the radial arm and is rotatable independentof the radial arm, and on thetable-suri'ace are mounted two levels Z Z.Referring now to Fig. 3, We will suppose it is desired to get thedistances from B to C or from A to C. The instrument, Fig. 1, is placedat B and the remote object C is sighted through the compass. The compassis then turned ninety degrees to establish the position ofthe base-lineAB. The distance A B is then measured oli for a baseline. The instrumentis next taken to A, and the compass is sighted back to B with scale Grcoincident with base-line A B, and the position of the compass is noted.rlhe compass is then turned and sighted to the remote object C, and theangle B A C is obtained. Now by means of the traverse-screw U the radialarm R and extension R are adjusted into alinement with the lastsight-line A C, and the distance B C oi' Fig. 3 will be read on thetangent-bar T and the distance A C will be read by the added readings ofR and R'. Ii' instead of a compass a transit is used having anadjustment in a vertical plane it is obvious that any height C B ordistance A C to an elevated point may be obtained in like manner.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is-

1. A trigonometrical meter, comprising a pivoted radial arm having' asliding and graduated extension, a graduated and stationary base-linescale, a stationary graduated tangent-bar. a parallel-motion sine-barpivoted to the radial arm and means for moving the radial armsubstantially as shown and described.

2. A trigonometrical meter, comprising a pivoted radial arm having asliding and graduated extension, a graduated and stationary base-linescale, a stationary and graduated tangent-bar, a graduated sine-barpivoted at one end to the outer end of the radial arm, a second radialarm of equal length to the first pivoted to the other end of thesine-bar and having a stationary pivot at its other end and means formoving the radial arms and sine-bar substantially as shown anddescribed.

3. A trigonometrical meter, comprising a slotted table having agraduated tangent-bar iiXed to the table parallel to its slot, atraversescrevv arranged beneath the table parallel to the slot, apivoted radial arm having an eX- tensible section graduated as describedand having' a pin traversing the screw and a parallel-motion sine-barpivoted to the outer end of the radial arm substantially as shown anddescribed.

4. A trigonometrical meter comprising a pivoted radial arm having asliding and graduated extension, a graduated and stationary base-linescale, a stationary graduated tangent-bar, a parallel-motion sine-barpivoted to the radial arm, means for moving the radial arm and sine-bar,and a compass independently pivoted over.-the center of the radial armsubstantially asidescribed.

HARRY C. PERCY.

Witnesses:

ANeUs FLEMING, J. H. HICKS.

